Police are investigating attacks on dolphins in the Gulf of Mexico after some have been found with gunshot wounds, cuts and missing jaws.

The Sun Herald newspaper reports that the National Oceanic and Atmospheric Administration (NOAA) has issued a "heads up" directive on the matter.

Now officials are on alert for an increase in human interaction with dolphins in the waters off of Louisiana, Mississippi and Alabama.

Cases of gunshot wounds, mutilations and other injuries have been found, authorities say.

Scientists from the Institute for Marine Mammal Studies (IMMI) in Gulfport, Mississippi, recently found a dolphin dead from a 9mm bullet wound.

"It went through the abdomen, into the kidneys and killed it," said Moby Solangi, IMMS executive director.

On Friday, a team found a second dolphin dead on island off Mississippi with a portion of his jaw missing, and a dolphin was found in Alabama in recent months stabbed to death with a screwdriver.

Others have suffered what appear to be knife cuts.

Killing dolphins is a federal offence, and a conviction for harassing, harming, feeding or killing wild dolphins carries a fine of up to $100,000 (£63,000) and a one-year jail sentence.

Feeding wild dolphins causes them to become so accustomed to humans and boats that they make attempts to prey on hooked bait and catches, creating conflicts with fishermen, NOAA said in a press release.